It is only about thirty centimetres deep, unimpressive by most measures, and yet it represents one of the most widespread and still somewhat mysterious monument types in the Irish prehistoric landscape.

This is what archaeologists call a burnt mound, or in Irish a fulacht fiadh, a feature found in the thousands across Ireland, typically dating to the Bronze Age. The general interpretation is that these sites were used for heating water, by removing stones from a fire and dropping them into a trough until the water boiled, though debate continues about whether they served for cooking, bathing, textile processing, or some combination of purposes. What they leave behind is always the same: a crescentic or oval spread of heat-shattered stone and fire-blackened soil, the accumulated debris of repeated burning over many sessions. The example at Moanroe fits this pattern closely, its modest spread and thin depth suggesting a site that was used with some regularity but was never especially large in scale. An east to west drain has been cut through the middle of the spread at some later point, slicing across the archaeology in the way that agricultural and drainage works so often do across low-lying Irish ground.